For the sake of convenience of transportation, reducing costs of later processing and other reasons, thermoplastic resin is normally produced and distributed in the form of pellets, which are small, approximately rice-grain sized particles. These pellets are produced industrially by means of a kneading pelletizing (extrusion) machine incorporated in a chemical apparatus. Examples of types of a pelletizing device used in such a pelletizer include a hot cut type and a underwater cut type. There are also various blades used for this purpose; a typical example of fixed blades is a die plate, while there is a cutter knife 1 shown in FIG. 8 as an example of movable blades. Nowadays, because of their superior abrasion resistance and resin cutting capability, ceramic alloys are most widely used as a material of cutter knife 1.
However, ceramic alloys used as a material of such a cutter knife present various problems; not only are they expensive and hard to acquire but also prone to being chipped or broken because they have lower resistance to a transverse load, in other words are more fragile, compared with steel which is the most typical blade material. Although ceramic alloys require a thorough countermeasure to solve the above problems, it cannot be said that a sufficiently effective countermeasure exists at present. Furthermore, a ceramic alloy is difficult to process by using machine, which means that processing a ceramic alloy is costly. Therefore, using a ceramic alloy, which is itself an expensive material, to produce cutter knives substantially increases their costs.
A prior art method of producing a ceramic alloy cutter knife uses a process of sintering powdered ceramic alloy directly to two large base metal bodies by using a special container and then subjecting the contents to a hot isostatic pressing (HIP) process. The bodies are removed from the container and separated from each other. Each body is then cut along its longitudinal axis which is directly in the middle of the ceramic alloy material. Each half is then cut again into individual pieces or blanks, which are in turn cut again and formed into individual cutter knives. In addition, the process requires that the ceramic alloy be ground into a knife edge. The powdered ceramic alloy HIP process is complicated and presents various technological difficulties, for example, the air must be removed from the container prior to sintering which naturally results in the discharge of some of the powdered material. The entire production method is expensive and does not alleviate any problems associated with fragility of the ceramic alloy blade or that of avoiding unnecessary processing. In addition, powdered ceramic alloy material is less available and must be specially procured from a powder manufacturer. In short, the prior art method does not address the problems associated with producing a ceramic alloy cutter knife in terms of expense, the delicate nature of the material, availability of ceramic alloy material and the reduction of processing of the blade.